Steel alloy.



UNI ED STATES PATENT OFFICE.

WILLIAM BEARDMORE, OF GLASGOW, SCOTLAND.

1,007,055. N Drawing.

Specification of Letters Patent.

fs'rnnr. ALLOY.

v This invention relates to the manufacture of steel, the chief object being to provide a steel alloy or composition for use more particularly in making armor plates and gun tubes, and to obtain the requisite properties which are desirable in steel intended for these purposes by using only a comparatively small percentage of carbon.

According to this invention the steel besides having a low percentage of carbon 0011- tain's metallic constituents other than" ferrite, which constituents are ofsuch a character and are used in such proportions that the strength and toughness of the steel are afforded by the solution of. the saidconstitu ents 1n the ferrite. The proportion of car-- bon in the steel is so low that the hardening carbon formed on heating the steel above the first critical point-Ac (but not above the second critical point Ac has little effect upon the toughness. The carbon should not exceed .25 per cent. The most important of the metallic constituents I employ are molybdenum and nickel. I The composition of a steel which I-have found satisfactory is. as follows :carbon 0.15 to 0.25 per cent., molybdenum. 1.00 to 2.00 per cent., nickel 5.00 to 7 .00, per cent, tungsten not exceeding 3.00 per cent, manganese not exceeding 0.70 per cent. -In addition-to the above stated constituents the 49 steel would contain some small percentage of sulfur and phosphorus which however should of course be as small as possible;

Steel of a composition similar to that above stated is suitable not only in theman ufacture of gun tubes and armor ,plates but also for certain classes of armor and shields for small guns. Owing, however, to the unusually. low percentage of carbon, the steel ,does' not harden by mere quenching when 50 hot, sufiiciently' to impart to it a face of the extreme hardness necessary for the purpose above mentioned, and the steel must therefore besubjected to a process of cemen'tation. Not until after the steel has had its face cemented and differentially hardened does it possess the requisite extreme face hardness.

By suitably regulating the degree and extent of differential treatment to "which thesteel plates may be. subjected, it is possible to secure great hardness in some parts while retaining at other parts a ductile and tough condition. In the case of armor plates the qualities possessed by the steel enable them after \cementation'to resist the penetration Patented Oct. 31,1911.

Application filed December 5, 1910. Serial No. 595,721.

of modern capped projectiles and at the same time to resist the racking action of the projectiles, particularly in the case of plates of less thickness than the caliber of the guns used in attacking them. In the case of steel for gun tubes, an increased resistance to bursting or cracking of the tube by the shock of discharge is obtained.

What I claim and desire to secure by Letters Patent of the United States is 1. Steel for use in the manufacture of armor plates, containing in addition to the usual ferrite, a percentage of carbon not exeeding .25, and molybdenum and nickel in proportions sufficient to compensate for the deficiency in the strength and toughness of {she steel due to the low percentage of caron. I

2. Steel for use in the manufacture of armor plates,. containing, inaddition to the usual ferrite, a percentage of carbon not exceeding .25, and molybdenum, nickel, and tungsten, in proportions sufficient to compensate for the deficiency in the strength and toughness of the steel due to the low percentage of carbon.

-3. Steel for use in the manufacture of armor plates, comprising, in addition to the usual ferrite, .15 to .25 per cent. of carbon, 1.00 to 2.00 per cent. of molybdenum, 5.00 to 7.00 per cent. of nickel, tungsten not exceeding 3.00 per cent., and manganese not exceeding 0.70 per cent.

.In testimony whereof I afiix my signature in presence of two witnesses.

WM. BEARDMORE. Witnesses:

A. M. MITCHELL, HARMON O. A 

